Studies will be carried out to determine the structural basis of the interaction of the alpha 1 chain of collagen with collagen:glucosyltransferase in order to determine its role in platelet-collagen adhesion. Structural studies on glycocalicin, the platelet receptor for thrombin and ristocetin/factor VIII, will also be carried out. BIBLIOGRAPHIC REFERENCES: T. Okumura and G.A. Jamieson. Platelet Glycocalicin: A Single Receptor for Platelet Aggregation Induced by Thrombin or Ristocetin. Thromb. Res. 8:701-706 (1976). Tadayoshi Okumura and G.A. Jamieson. Platelet Glycocalicin: I. Orientation of Glycoproteins of the Human Platelet Surface. J. Biol. Chem. 251:5944-5949 (1976).